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authorWill Deacon <will.deacon@arm.com>2011-09-23 14:34:12 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2011-09-26 12:36:47 +0100
commitdf77abcafc8dc881b6c9347548651777088e4b27 (patch)
tree1311e860f1c86371852175c582d111ce565d411d /arch
parentd8e89b47e00ee80e920761145144640aac4cf71a (diff)
downloadlinux-df77abcafc8dc881b6c9347548651777088e4b27.tar.gz
ARM: 7099/1: futex: preserve oldval in SMP __futex_atomic_op
The SMP implementation of __futex_atomic_op clobbers oldval with the status flag from the exclusive store. This causes it to always read as zero when performing the FUTEX_OP_CMP_* operation. This patch updates the ARM __futex_atomic_op implementations to take a tmp argument, allowing us to store the strex status flag without overwriting the register containing oldval. Cc: stable@kernel.org Reported-by: Minho Ban <mhban@samsung.com> Reviewed-by: Nicolas Pitre <nicolas.pitre@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch')
-rw-r--r--arch/arm/include/asm/futex.h34
1 files changed, 17 insertions, 17 deletions
diff --git a/arch/arm/include/asm/futex.h b/arch/arm/include/asm/futex.h
index 8c73900da9e..253cc86318b 100644
--- a/arch/arm/include/asm/futex.h
+++ b/arch/arm/include/asm/futex.h
@@ -25,17 +25,17 @@
#ifdef CONFIG_SMP
-#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg) \
+#define __futex_atomic_op(insn, ret, oldval, tmp, uaddr, oparg) \
smp_mb(); \
__asm__ __volatile__( \
- "1: ldrex %1, [%2]\n" \
+ "1: ldrex %1, [%3]\n" \
" " insn "\n" \
- "2: strex %1, %0, [%2]\n" \
- " teq %1, #0\n" \
+ "2: strex %2, %0, [%3]\n" \
+ " teq %2, #0\n" \
" bne 1b\n" \
" mov %0, #0\n" \
- __futex_atomic_ex_table("%4") \
- : "=&r" (ret), "=&r" (oldval) \
+ __futex_atomic_ex_table("%5") \
+ : "=&r" (ret), "=&r" (oldval), "=&r" (tmp) \
: "r" (uaddr), "r" (oparg), "Ir" (-EFAULT) \
: "cc", "memory")
@@ -73,14 +73,14 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
#include <linux/preempt.h>
#include <asm/domain.h>
-#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg) \
+#define __futex_atomic_op(insn, ret, oldval, tmp, uaddr, oparg) \
__asm__ __volatile__( \
- "1: " T(ldr) " %1, [%2]\n" \
+ "1: " T(ldr) " %1, [%3]\n" \
" " insn "\n" \
- "2: " T(str) " %0, [%2]\n" \
+ "2: " T(str) " %0, [%3]\n" \
" mov %0, #0\n" \
- __futex_atomic_ex_table("%4") \
- : "=&r" (ret), "=&r" (oldval) \
+ __futex_atomic_ex_table("%5") \
+ : "=&r" (ret), "=&r" (oldval), "=&r" (tmp) \
: "r" (uaddr), "r" (oparg), "Ir" (-EFAULT) \
: "cc", "memory")
@@ -117,7 +117,7 @@ futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr)
int cmp = (encoded_op >> 24) & 15;
int oparg = (encoded_op << 8) >> 20;
int cmparg = (encoded_op << 20) >> 20;
- int oldval = 0, ret;
+ int oldval = 0, ret, tmp;
if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
oparg = 1 << oparg;
@@ -129,19 +129,19 @@ futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr)
switch (op) {
case FUTEX_OP_SET:
- __futex_atomic_op("mov %0, %3", ret, oldval, uaddr, oparg);
+ __futex_atomic_op("mov %0, %4", ret, oldval, tmp, uaddr, oparg);
break;
case FUTEX_OP_ADD:
- __futex_atomic_op("add %0, %1, %3", ret, oldval, uaddr, oparg);
+ __futex_atomic_op("add %0, %1, %4", ret, oldval, tmp, uaddr, oparg);
break;
case FUTEX_OP_OR:
- __futex_atomic_op("orr %0, %1, %3", ret, oldval, uaddr, oparg);
+ __futex_atomic_op("orr %0, %1, %4", ret, oldval, tmp, uaddr, oparg);
break;
case FUTEX_OP_ANDN:
- __futex_atomic_op("and %0, %1, %3", ret, oldval, uaddr, ~oparg);
+ __futex_atomic_op("and %0, %1, %4", ret, oldval, tmp, uaddr, ~oparg);
break;
case FUTEX_OP_XOR:
- __futex_atomic_op("eor %0, %1, %3", ret, oldval, uaddr, oparg);
+ __futex_atomic_op("eor %0, %1, %4", ret, oldval, tmp, uaddr, oparg);
break;
default:
ret = -ENOSYS;